import random

# 单继承
class Animal:
    def sound(self):
        pass
    def walk(self):
        print('animal is walking')

class Dog(Animal):
    def sound(self):
        return "Woof!"

class Cat(Animal):
    def sound(self):
        return "Meow!"
    
# 多继承
class Thing:
    id :int
    def __init__(self) -> None:
        self.id = random.randint(1000000, 99999999)

class Goods:
    price :float = 1
    isSall = True
    
class Cake(Thing, Goods):
    pass
